RMAN - unregister database from recovery catalog

SQL> select db_key, db_name, reset_time, dbinc_status from RMANCAT.DBINC where db_name = 'MYRACDB' ;

DB_KEY DB_NAME RESET_TIME DBINC_ST
---------- -------- ----------- --------
91068668 MYRACDB 17-nov-2010 PARENT
91068668 MYRACDB 12-mar-2008 PARENT
91068668 MYRACDB 02-may-2011 CURRENT
91068668 MYRACDB 28-apr-2011 ORPHAN
91068668 MYRACDB 27-apr-2011 ORPHAN
91068668 MYRACDB 27-apr-2011 ORPHAN
91068668 MYRACDB 28-apr-2011 ORPHAN

7 rows selected.

SQL> select db_key, db_id from RMANCAT.DB where DB_KEY=91068668;

DB_KEY DB_ID
---------- ----------
91068668 232532794

Now Login as RMAN

${ORACLE_HOME}/bin/rman catalog rmancat/cat@rmandb.world.com

RMAN> set dbid=232532794;

RMAN> unregister database ;

database name is "MYRACDB" and DBID is 232532794

Do you really want to unregister the database (enter YES or NO)? yes
database unregistered from the recovery catalog

RMAN>